Lash adjuster



y 24, 1960 c. VOORHIES 2,937,632

LASH ADJUSTER Filed June 8, 1956- 2 Sheets-Sheet 1 Fig. 6

In ven for". Car? Z200 7"]? 1'85 5y Par)???" C'arl'er fltzorneys y 24, 1960 c. VOORHIES 2,937,632

LASH ADJUSTER Filed June 8, 1956 2 Sheets-Sheet 2 United States Patent Ofiice 2,937,632 7 LASH ADJUSTER Carl Voorhies, 917 s. Knight, Park Ridge, 111.

' Filed June 8, 1956,-Ser.'N0. 590,219

20 Claims. cl. 123-90) Thisinvention relates to a lash adjusteror tappet and it has for one object to provide a lash adjuster which will operate at a predetermined clearance.

Another object is to provide a device of the type indicated which may be used'in internal combustion engines already in the field, including a cam shaft design to operate with adjustable tappets.

Another object is to provide a device of the type indi cated which may be embodied either in a tappet in contact with the cam shaft or anywhere in the valve linkage.

Other objects will appear from time to time throughout the specification and claims. i

The invention is illustrated more .or less diagrammatically in the accompanying drawings wherein:

Fig. l is a plan view of one form of the device of this invention embodied in a tappet;

Fig. 2 is a vertical section taken at line 2-2 of Fig. 1';

Fig. 3 is a section similar to Fig. 2' but illustrating a modified form; v

Fig. 4 is a generally vertical section showing the device of Figs. 1 and 2 embodied in the push rod or associated with the push rod of the valve linkage;

Fig. 5 is a side elevation .on a reduced scale showing the device in the form of Fig. 4 and showing-the essential elements of the valve gear; and

Fig. 6 is anelevatio'nal view of the valve cag'e. Like parts are designated by'like characters throughout the specification and drawings.

1 indicates generally a portion of an engine. 2 is a cam shaft carrying one or'more cams3. The engine portion l may have a perforation or bore formed in it and within this perforation, bore or cavity is mounted a liner 4. The liner 4 maybe flanged as at 5 if desired.

A tappet body 6 is provided for reciprocation within the liner 4 and is provided with a closed 'end'7. The tappet body is of generally-cylindrical shape and is open at its upper end as at 9. It is provided with agroove 10 Within which a retaining member 11 is removably'positioned.

A ho'llow plunger 12 is mounted for reciprocation within the cylindrical tappet body 6. It is reduced at one end as at 13 and a bore 14 extends through the reduced portion. The bore 14 is outwardly flared a's'at 15 and the outer end of the reduced portion 13 is beveled as at 16. The flared portion 15 and thebevel 16 provide .a relatively narrow annular valve seat "1 7 against which a flat valve member 18 is adapted to be seated. member is provided with a reduced extension 19 LA valve cage-20 is positioned aboutthe reduced port1on 13 and 1 overlies the valve 19 to hold it in place generally adjacent the valve seat 17. The valve cage is of sufficient size to permit the valve to move away from the valve seat and thus to open the passage 14 for liquid flow therethrough. 7

At its upper end the plunger '12 is closed by a cap 21 which is provided with an integral reduced portion 22. Within the cap 21 is formed a hemispherical seat 23 and a liquid passage 24 extends frorn the seat 23 to'the interior of the plunger 12. The retaining member 11 limits the outward movement'of the cap 2'1'and the'plunger12.

Patented May 24,' 1960 As shown, the closed end 7 of the tappet body 6 isin contact with the cam 33. At its upper-end a push rod 25 whlch terminates in a generally spherical member 26 forms a part of the valve linkage, the member 26 being movably positioned in the sink 23. A lubricant passage 27 extends through the rod 25 and the spherical portion 26 and is generally in communication with the passage .24 in the cap 21.

A counterbore 28 is formed in the plunger :12. and .ter minates in a shoulder 29. A groove 30 is formed in the outer face of the reduced portion 22 of the-cap 21. The counterbore 28 is preferably of less depth than the width of the groove 30. Thus a clearance 31 may exist between the upperend of the plunger 12 and the lower .face of the main portion of the cap 21.

A spring 32 is positioned within the spaced defined by changes which will now be described. A split ring 341's positioned within the space defined by the counterbore 28 of the groove 3%) and a spring'35 is positioned within this space. It bears at one end upon the ring 34 and at the other end :it bears upon the lower face of the cap 21..

The spring 32 is formed of material of generallyrangular or squared cross section, while the spring 35 is formed of material of round cross section. With the .exceptionof the members 34- and 35, the construction shown in Fig. 3 is identical with that shown in Fig. 2. The parts are therefore notredescribed andbearthe same reference characters as shown in and described-in connection with Figs.land2. 7 I

m In the form of Figs. 4 and 5 the purpose of the-device is the same as that of the earlier forms. The device dilfers from the earlier forms only by reason of the fact that it is positioned away from the cam and elsewhere As shown, the member 36 is the in the valve link age. equivalent of the tappet body .or cylinder 6. .It is provided with a closed end 37.from .which extends a reduced portion 3$ which fits into a member 39 fixedto or formed as a part of a push ro'd:40.' The push-rod may be engaged with a tappet 41 which has a mushroomhead 42. The device of Figs. 4 and 5 may be embodied in a .construction in which almost any type of tappetis usedin contact with the cam. The invention is not limited,

therefore, to the details of the tappet construction in the form of Figs. 4 and 5 and those details willnot be further described.

The upper end of the cylindrical body 36 is open as at reference numerals and will not be redescribed.

A rockerarm 43 is carried upon a tubular member44. At one, end of the rocker arm is a generally spherical member 45 which is seated in the hemispherical seat 23in the cap 21. A bore 46, generally the equivalent of the bore 27, extends through the rocker arm 43 and the spherical member 45 and communicates with the passage 24. The member 44 is generally stationary and maybe carried by one or more supports 4'7. These structures are con- I vent-ional and their details form no essential part of the presentinvention. It is suflicient for the purposes oflthe invention in the forms shown in Figs. 4 and 5 that lubricant fluid be supplied through the rocker arm to the lash adjuster. The member 44 is provided with openings 48 opposite each rocker arm so that the bore 46 is in communication with an opening 48 through which fluid from the hollow bore of the member 44 reaches the bore and thus reaches the lash adjuster.

The rocker arm 43 as shown in Fig. 5 bears at one end upon a valve stem 49 upon which the abutment 50 is fixed. A valve spring 51 bears against the abutment and is biased to raise the valve stem. The engine valve which is operated by the movement of the'rocker arm and the valve spring 51 is conventional and the present invention is not limited to any particular details of this device. The construction of the push rod 40 and its engagement with the cylinder 36 may be varied widely. The cylinder 36 at its closed end may be shaped in any desired shape and reduced and the push rod may carry an enlargement to receive the reduced end of the cylinder 36. On the contrary, the end of the cylinder 36 may be provided with a cavity into which the push rod 40 is received. The precise details of this part of the construction form no essential part of the present invention. It is sufficient for the purposes of the invention that the device in Figs. 4 and 5 be so arranged that the cylinder 36 is engaged with the push rod 40 which is engaged with a tappet of any desired shape.

Another feature which is shown but which is not essential to the present invention is the spring 20a which is shown within the valve cage 20. This may be in the form of a washer spring, as shown, and it is biased to seat the valve 19. In some installations this spring 26a may be omitted or a spring of another construction may be used, if desired, instead of the washer spring.

In all forms of the device a plunger spring 52 is mounted to bear upon the closed end of the cylinder and upon the plunger. It is biased to move the plunger away from the closed end and it is of less load than the cap springs 32 or 35 and of less load than the valve spring 51.

Although I have shown an operative form of my device, the invention is not limited to the particular details shown. Many changes may be made in the fo shape and arrangement of parts without departing from the spirit of the invention. 7

Other types of oil feed may be used. The type of oil feed shown in Fig. 2 of Voorhies Patent No. 2,682,865, issued July 6, 1954, might be used equally well. The invention is not limited to any particular type of oil feed.

The use, operation and function of the invention are as follows:

Under some conditions it is desirable to accomplish an automatic adjustment of the valve gear of an internal combustion engine and at the same time to maintain a predetermined amount of clearance. This may occur when engines already in use in the field develop some problem requiring automatic adjustment where the cam shaft originally installed in such engines has been designed to operate with an adjusted clearance. If into such an engine a lash adjuster designed to operate at substantially zero clearance were to be installed, the valve timing would be altered, thus making the timing poor or wholly defective, particularly when idling. Other factors may also be altered and the performance of the engine thus adversely effected.

To provide a hydraulic lash adjuster suitable for use under such conditions is one of the objects of the present invention. This lash adjuster has a. built-in clearance feature which will provide the required amount of clearance. Therefore, with the lash adjuster of this invention installed in such an engine, the performance of the engine will be at least as good as that with the adjustable tappets for which it may have been designed. There is the further advantage that with the use of the lash adjuster of this invention the necessity for frequent adjustments is avoided. Without the use of the present lash adjuster,

fi'equent adjustments are necessary to maintain satisfactory clearance throughout the temperature ranges which occur under operating conditions. The lash adjuster of this invention is not, therefore, a mere replacement device, but it is a device for improving the operation of an engine designed originally for an adjusted clearance in the valve gear.

Another advantage is that the present structure provides a hydraulic lash adjuster which can be used where hydraulic lash adjusters are considered optional. Because of the clearance feature which they provide, the same cam contour may be used in the engine for both the hydraulic and the adjustable tappets or lash adjusters. The two uses of the device, and hence the two objects of the device just above mentioned, are merely illustrative. Other uses exist and the invention is not limited to the particular uses mentioned. The means of the present invention constitute in a single device the hydraulic lash adjuster or tappet and the means for maintaining the necessary clearance. The device of this invention has the important advantage that it may be made accurately and economically. Accuracy is maintained by the fact that the groove in the cap can be readily made with a single tool so that the width of the tool controls the width of the groove with minute accuracy. Similarly, the counterbore in the plunger can be made with a single tool facing. Thus the counterbore can be made with extreme accuracy and economy. Since the width of the groove in the cap is somewhat wider than the length of the counterbore, the degree or extent of clearance is established readily by this fact. A clearance of the extent desired is thus achieved by proportioning the width of the groove to the length of the counterbore. The clearance is thus equal to the amount by which the width of the groove in the cap exceeds the length of the counterbore in the plunger.

When the lash adjuster is assembled in the valve gear of an engine, whether it be embodied in the tappet or positioned elsewhere in the gear between the cam shaft and the engine valve, the plunger spring is biased to force the plunger outwardly from the cylinder and the cap spring is biased to force the cap outwardly. The cap spring is of higher load than the plunger spring, and the cap spring will, when free to do so, bring the bottom of the counterbore and the bottom of the inner end of the groove to a position in line with each other, thus leaving a clearance between the seat or flange of the cap and the top of the plunger.

Since the cap spring has a greater load than the plunger spring, this clearance will be maintained during the time when the lash adjuster is filled with oil, but the cap spring will be compressed and the clearance will be taken up as the cam operates the valve gear. When the cam is in such position that it operates the valve gear it forces the cylinder upwardly and compresses the cap spring sufficiently to take up the clearance between the cap and the upper end ,of the plunger.

In the manner justdescribed the valve gear will operate with a clearance equal to the difference in length between the groove in the cap and the depth of the counterbore.

In one form of the device, that in which the cap spring formed of stock of rectangular cross section is used,

vthe spring itself bears against the end of the counterbore andthe end of the cap groove and is biased to bring them in line with each other. In the alternate form, where a spring of round cross section material is used, a ring is positioned within the space bounded by the cap groove and the plunger counterbore. Thus, this ring bears against the end of the counterbore and the end of the cap groove and furnishes a fiat surfacc for the spring of round cross section and by this construction the spring may bring the bottom of the counterbore and the bottom of the groove to a position in line with each other. The ring will preferably be made in the form of a split ring of two semicircular members or parts so that it can be readily positioned about the cap and within the cap groove without inconvenience and without distortion which might occur if it were a unitary member sprung or forced into place. In either .form of the device a cap spring is provided of greater load than the plunger spring biased to bring the bottom of the counterbore and the bottom of the groove into line to maintain the clearance. When the clearance is taken up as the cam operates the valve gear, the plunger and cap move relatively toward each other so that the clearance disappears and the cap flange is in contact with the upper or outer end of the plunger. In thatcase the bottom or inner end of the cap groove is below the bottom of the plunger counterbore. When the cam ceases to operate the valve,

the cap spring is then free to establish the clearance.

I claim: 1. In combination in a lash adjuster a cylinder having a closed end and an open end, a'hollow plunger mounted within said cylinder for longitudinal movement therein, a spring positioned within said cylinder and bearing against said plunger and said cylinder and biased to move said plunger longitudinally with relation to said cylinder, and a cap positioned within said plunger and adapted for limited relative longitudinal movement with respect to said plunger, and a spring positioned between, enclosed by said cap and plunger jointly and bearing against said cap and said plunger positioned between them and biased'to move said cap outwardly with respect to said plunger, said second spring being of higher load than said first spring.

2. In combination in a lash adjuster a cylinder having a closed end and an open end, a hollow plunger mounted within said cylinder for longitudinal movement therein, a spring positioned within said cylinder and bearing against said plunger and said cylinder and biased to move said plunger longitudinally outwardly with relation to said cylinder, and a cap positioned within said plunger and adapted for limited relative longitudinal movement with respect tosaid plunger, and a spring positioned between, enclosed by said cap and plunger jointly and hearing against said cap andsaid plunger positioned between them and biased to move said cap outwardly with'respect to said plunger, said second spring being of higher load thansaid first spring.

3. In combination in a lash adjuster a cylinder having a closed end and an open end, a hollow plunger mounted within said cylinder for longitudinal movement therein, a spring positioned within said cylinder and bearing against said plunger and said cylinder and biased to move said plunger longitudinally with relation to said cylinder, and a cap positioned within said'plunger and adapted for limited relative longitudinal movement with respect to said plunger, and a spring within said plunger positioned between, enclosed by said cap and plunger jointly and bearing against said cap and said plunger positioned between them and biased to move said cap outwardly with respect to said plunger, said second spring being of higher load than said first spring.

4. In combination in a lash adjuster a cylinder having a closed end and an open end, ahollow plunger mounted within said cylinder 'for longitudinal movement therein, a spring positioned within said"'cylinder and bearing against said plunger and said cylinder and biased to move said plunger longitudinally outwardly with relation to said cylinder, and a cap positioned within said plunger and adapted for limited relative longitudinal movement with respect to said plunger, and a spring within said plunger positioned between, enclosed by said cap and plunger jointly and bearing against said cap and said plunger positioned between them and biased to move said cap outwardly with respect to said plunger, said second spring being of higher load than said first spring.

5. In combination in a hydraulic lash adjuster a cylinder, means closing one end thereof, a hollow plunger mounted within said cylinder for axial movement, a plunger spring positioned within said cylinder bearing and ,biased-to move the-plunger, the end of's'aid plunger away from fthe closed end of said cylinder having afcoimterbore extending :thereinto, a cap provided with a portion of substantially the same diameter as the interior of said plunger, and provided with a portion of larger diameter, said cap being grooved'ion its exterior intermediateitsends, said groove being of greater width than the length of said counterbore, and a spring positioned within the space defined .by said groove and said counterhere, said spring biased to move said cap outwardly with respectto'lsaid plunger and having a higher load than that of the said plunger spring said spring contacting the end of said counterbore and the inner end of said groove.

6. In combination'in a hydraulic lash adjuster a cylinder, means closing'one end thereof, a hollow plunger mounted within said cylinder for axial movement, a plunger spring positioned within said cylinder bearing against the closed end thereof and against said plunger and biased to move the plungerout'wardly, the end of said plunger away from the closed end of said cylinder having a counterbore xtending'thereinto, a cap provided with a portion of substantially thesame diameter as the interior of said plunger and provided with a portion-of larger diameter, said cap being grooved on its exterior,

intermediate'its ends, said groove being of greater'width thanthe length of "said counterbore, and aspring positioned within the space defined by said groove and said counterbore, said spring biased to move said cap outwardly with respect to "said plunger and having a higher load thantha t of th'e'said plunger spring, said spring contacting the endo'f saidcounte'rbore and the inner end of said groov e I 7. In combination in ajhy'draulic lash adjuster a cylinder, means closing one end thereof, a hollow plunger mounted within said cylinder for axial movement, a plunger spring positioned within said cylinder bearing against the closed end thereof and against said plunger and biased to movet'he plunger, the end of said plunger away from the closed end ofsaid cylinderhaving a counterbore extendingthe'reinto and defining a spring seat withinsaid plunger, acap provided with a portion of substantiallythe same diameter as the interiorof said plunger and provided with a portion oflarger diameter,

said cap beinggroovedon its exterior intermediate-it s ends, said groove being of greater width than the length of said counterbore, and a spring positionedwithin the space defined by said groov and said counterbore, said spring biased to move said cap'outwardly with'r'espect to said plunger and having a higher load than that of the said plunger spring, said spring contacting the cadet said counterbore and the inner end of said groove.

-8. In combination in a hydraulic'lashadjuster ac'y lindergmeans closing one end thereof, a hollow plunger mounted within said cylinder for axial movement, a

plunger spring positioned within said cylinder bearing against the closed end thereof and against said plunger and biased to move the plunger, the end of said plunger away from the closed end of said cylinder having a counterbore extending thereinto and defining a portion of greater diameter than that of the interior of said plunger and defining a spring seat withinsaid plunger, a cap provided with a portion of substantially the same diameter as the interior of said plunger and-provided with a portion of larger diameter, said cap being grooved on its:

9. In combination in a hyraulic lash adjuster a cylinder, means closing one end thereof, a hollow plunger mounted within said cylinder for axial movement, a plunger spring positioned within said cylinder bearing against the closed end thereof and against said plunger and biased to move the plunger outwardly, the end of said plunger away from the closed end of said cylinder having a counterbore extending thereinto and defining a portion of greater diameter than that of the interior of said plunger and defining a spring seat within said plunger, a cap provided with a portion of substantially the same diameter as the interior of said plunger and provided with a portion of larger diameter, said cap being grooved on its exterior intermediate its ends, said groove being of greater width than the length of said counterbore, and a spring positioned within the space defined by said groove and said counterbore, said spring biased to move said cap outwardly with respect to said plunger and having a higher load than that of the said plunger spring, said spring contacting the end of said counterbore and the inner end of said groove.

10. In a hydraulic lash adjuster a cylinder having one closed end and an opposite open end, a hollow plunger mounted for reciprocation within said cylinder, said plunger having a restriction adjacent its inner end, said restriction shaped to define a passage from the interior of said plunger, a valve positioned outside of said plunger adjacent said passage, a cage positioned outside of said valve and fixed to said plunger, a plunger spring positioned within said cylinder and between it and said plunger and biased to move said plunger outwardly away from the closed end of said cylinder, said plunger at its end away from said valve having a counterbore extending from its outer end inwardly, and a cap mounted within said plunger for limited reciprocation therein, said cap having a portion extending into the main diameter of said plunger, a lateral enlargement, said cap being grooved about its exterior, said groove being generally in opposition to said counterbore and of slightly greater width than the length of said counterbore, and a spring positioned in the space defined by said groove and said counterbore and in part lying within said groove and in part within said counterbore and bearing against said plunger and said cap, said spring biased to move said cap outwardly with respect to said plunger and having a higher load than the said plunger spring.

11. In a hydraulic lash adjuster a cylinder having one closed end and an opposite open end, a hollow plunger mounted for reciprocation within said cylinder, said plunger having a restriction adjacent its inner end, said restriction shaped to define a passage from the interior of said plunger, a valve positioned outside of said plunger adjacent said passage, a cage positioned outside of said valve and fixed to said plunger, a plunger spring positioned within said cylinder and between it and said plunger and biased to move said plunger outwardly away from the closed end of said cylinder, said plunger at its end away from said valve having a counterbore extending from its outer end inwardly, a cap mounted within said plunger for limited reciprocation therein, said cap having a portion extending into the main diameter of said plunger, a lateral enlargement overlying the end of said plunger, said cap being grooved about its exterior, said groove being generally in opposition to said counterbore and of slightly greater width than the length of said counterbore, and a spring positioned in the space defined by said groove and said counterbore and in part lying within said groove and in part within said counterbore and bearing against said plunger and said cap, said spring biased to move said cap outwardly with respect to said plunger and having a higher load than the said plunger spring.

12. In a hydraulic lash adjuster a cylinder having one closed end and an opposite open end, a hollow plunger mounted for reciprocation within said cylinder, said plunger having a restriction adjacent its inner end, said restriction shaped to define a passage from the interior of said plunger, a valve positioned outside of said plunger adjacent said passage, a cage positioned outside of said valve and fixed to said plunger, a plunger spring positioned within said cylinder and between it and said plunger and biased to move said plunger outwardly away from the closed end of said cylinder, said plunger at its end away from said valve having a counterbore extending from its outer end inwardly, a cap mounted within said plunger for limited reciprocation therein, said cap having a portion extending into the main diameter of said plunger, a lateral enlargement of substantially the same diameter as the external diameter of said plunger and overlying the end of said plunger, said cap being grooved about its exterior, said groove being generally in opposition to said counterbore and of slightly greater width than the length of said counterbore, and a spring posi' tioned in the space defined by said groove and said counterbore and in part lying within said groove and in part within said counterbore and bearing against said plunger and said cap, said spring biased to move said cap outwardly with respect to said plunger and having a higher load than the said plunger spring.

13. In a hydraulic lash adjuster a cylinder having one closed end and an opposite open end, a hollow plunger mounted for reciprocation within said cylinder, said plunger having a restriction adjacent its inner end, said restriction shaped to define an exterior shoulder and a passage from the interior of said plunger, a valve positioned outside of said plunger adjacent said passage, a

cage positioned outside of said valve and fixed to said plunger, spring means positioned within said cage adapted to bear against it and said valve and biased to move said valve to seated position against the adjacent surface of said plunger, a plunger spring positioned within said cylinder and between it and said plunger and biased to move said plunger outwardly away from the closed end of said cylinder, said plunger at its end away from said valve having a counterbore extending from its outer end inwardly, a cap mounted within said plunger for limited reciprocation therein, said cap having a portion extending into the main diameter of said plunger, a lateral enlargement, said cap being grooved about its exterior, said groove being generally in opposition to said counterbore and of slightly greater width than the length of said counterbore, and a spring positioned in the space defined by said groove and said counterbore and in part lying within said groove and in part within said counterbore and bearing against said plunger and said cap, said spring biased to move said cap outwardly with respect to said plunger and having a higher load than the said plunger spring.

14. In a hydraulic lash adjuster a cylinder having one closed end and an opposite open end, a hollow plunger mounted for reciprocation within said cylinder, said plunger having a restriction adjacent its inner end, said restriction shaped to define an exterior shoulder and a passage from the interior of said plunger, a valve positioned outside of said plunger adjacent said passage, a cage positioned outside of said valve and fixed to said plunger, spring means positioned within said cage adapted to bear against it and said valve and biased to move said valve to seated position against the adjacent surface of said plunger, a plunger spring positioned within said cylinder and between it and said plunger and biased to move said plunger outwardly away from the closed end of said cylinder, said plunger at its end away from said valve having a counterbore extending from its outer end .inwardly and defining a shoulder, a cap mounted within said plunger for limited reciprocation therein, said cap having a portion extending into the main diameter of said plunger, and a lateral enlargement of substantially the same diameter as the external diameter of said plunger and overlying the end of said plunger, said cap being grooved about its exterior, said groove being generally in opposition to said counterbore and of slightly greater width than the length of said counterbore, and a spring positioned in the space defined by said groove and said counterbore and in part lying within said groove and in part within said counterbore and bearing against said plunger and said cap, said spring biased to move said cap outwardly with respect to said plunger and having a higher load than the said plunger spring.

15. In a valve gear for an internal combustion engine a cam shaft, a cam thereon, an engine valve, means biased to move said valve to closed position, a tappet for said cam, a push rod positioned to be moved by said tappet, a rocker arm positioned to be moved by said push rod, and means in said valve gear for establishing a predetermined clearance, said means including a pair of relatively movable tappet members and a spring between them and biased to extend them, each of said members shaped to provide together a space within which said spring is enclosed, the maximum movement of extension being determined by the relative length of said spaces.

16. In combination in an engine valve gear a valve, a spring biased to close it, means for opening it including a cam and a linkage between said cam and said valve, said linkage including a hydraulic lash adjuster comprising a cylinder and a two part plunger within said cylinder, a plunger spring in said cylinder of less load than said valve spring biased to move said plunger, a spring positioned between said two parts of said plunger and biased to move them to increase the length of said plunger, said last mentioned spring being of greater load than said plunger spring and of less load than said valve spring, the parts of said plunger shaped to provide a cavity within which said last mentioned spring is positioned, the amount of relative movement of said plunger parts being determined by the relative length of said parts.

17. In combination in an engine valve gear a valve, a spring biased to close it, means for opening it including a cam and a linkage between said cam and said valve, said linkage including a hydraulic lash adjuster comprising a cylinder and a two part continuous plunger Within said cylinder, a plunger spring in said cylinder of less load than said valve spring biased to move said plunger, a spring positioned between said two parts of said plunger and biased to move them to increase the length of said plunger, said last mentioned spring being of greater load than said plunger spring and of less load than said valve spring, each of the parts of said plunger shaped to provide a cavity within which a part of said last mentioned spring is positioned, the amount of relative movement of said plunger parts being determined by the relative length of said parts.

18. In combination in a hydraulic lash adjuster a cylinder, a two part continuous plunger mounted therein for reciprocation, means for maintaining a predetermined clearance between portions of said two parts comprising a groove in one part and a counterbore in the other, and. a spring positioned in the space defined by said groove and counterbore and biased to move said two plunger parts apart.

19. In combination in a lash adjuster a cylinder having a closed end and an open end, a hollow plunger mounted within said cylinder for longitudinal movement thereon, a spring positioned within said cylinder and bearing against said plunger and said cylinder and biased to move said plunger longitudinally with relation to said cylinder, and a cap positioned within said plunger and adapted for limited relative longitudinal movement with respect to said plunger, and a spring within said plunger bearing against said cap and said plunger and biased to move said cap outwardly with respect to said plunger, said cap and said plunger being shaped to provide seats for opposite ends of said last mentioned spring and to enclose together said spring, said second spring being of higher load than said first spring, and means for limiting the outward movement of said cap with respect to said plunger.

20. In combination in a lash adjuster a cylinder having within said cylinder for longitudinal movement therein, a spring positioned within said cylinder and bearing against said plunger and said cylinder and biased to move said plunger longitudinally with relation to said cylinder, and a cap positioned within said plunger and adapted for limited relative longitudinal movement with respect to said plunger, and a spring within said plunger bearing against said cap and said plunger and biased to move said cap outwardly with respect to said plunger, said cap and said plunger being shaped to provide seats for opposite ends of said last mentioned spring and to enclose together said spring, said second spring being of higher load than said spring, said last-mentioned spring positioned to act as a stop to limit the outward movement of said cap with relation to said plunger.

References Cited in the file of this patent UNITED STATES PATENTS 2,630,792 Engemann Mar. 10, 1953 2,682,865 Voorhies July 6, 1954 2,804,060 Bergmann Aug. 27, 1957 FOREIGN PATENTS 830,433 Germany Feb. 4, 1952 

